This application claims priority to German Patent Application 10048864.1 filed Oct. 2, 2000, which application is incorporated by reference herein.
This invention relates to a gas turbine with at least one combustion chamber, a combustion chamber wall, a metering panel, at least one heat shield, at least one sleeve and a cowling.
Various designs of combustion chamber heads are known in the state of the art. For example, combustion chambers are of the one-part annular type made up of several, inseparably connected components. The main components are the inner and the outer combustion chamber wall and the combustion chamber head. The combustion chamber head is either made as a single component, for example by casting, or of different components, such as sheet-metal fabrications, turned parts etc.
Known combustion chamber heads are taught in Specifications EP 841 520 A2, U.S. Pat. No. 5,524,430, EP 927 854 A2, U.S. Pat. No. 5,289,687 or U.S. Pat. No. 5,331,815.
Besides the one-part designs, combustion chamber heads are known which are made up of individual components joined together by bolt-type fastenings or similar means.
The known designs generally are characterized by a high assembly effort. In particular, assembly of the heat shield together with the sleeves to the metering panel is difficult with some of the known designs since it must be performed from the exit side of the combustion chamber. This involves a considerable increase of the assembly costs.
Furthermore, the known combustion chamber heads have zones which are problematic in terms of the supply of cooling air, these problems arising from the circumstance that the individual components may compromise the supply of cooling air to the heat shield in certain zones.
In the design known from EP 841 520 A2, the sleeve and the heat shield form a unit and are assembled together on the metering panel from the exit of the combustion chamber. In this design, the surface of the sleeve which faces the combustion chamber interior is liable to considerable heating and cannot be cooled effectively.
In a broad aspect, the present invention provides a combustion chamber head of the type specified at the beginning which combines simplicity of design and easy and cost-effective manufacture and assembly with the capability of effective cooling of the heat shield.
It is a particular object of the present invention to provide a combustion chamber head for a gas turbine, comprising: a combustion chamber outer wall; a combustion chamber inner wall; a metering panel; at least one heat shield; at least one sleeve; and a cowling; wherein the metering panel is formed as a unitary part with the combustion chamber outer wall and the combustion chamber inner wall, the heat shield is mounted to the metering panel from a downstream side of the metering panel, the sleeve is mounted to the metering panel from an upstream side of the metering panel, and the cowling is removably attached to the metering panel. Further objects and advantages of the invention will be apparent from the description below.
The combustion chamber head according to this invention is characterized by a variety of merits.
According to the present invention, the heat shield is mounted to the metering panel from the downstream side, whilst all other components are fitted from the upstream side of the metering panel. This method of assembly is far simpler since it dispenses with the need of fitting and securing bolt-type fastenings or similar means from the side of the combustion chamber interior. The removable cowling provides for free, undisturbed access to the assembly areas. Providing the cowling as an extra, removable, separate component enables the entire combustion chamber head to be assembled without any problems. Moreover, it is not necessary to provide the cowling with assembly openings or similar means as known in the prior art. Rather, the present invention provides for free, unhindered access to the upstream side of the metering panel.
A particularly favourable feature of the design according to the present invention is that the sleeves are installed from the upstream side of the metering panel. This feature provides for re-location of the sliding and sealing face away from the metering panel, enabling cooling air to reach also the inner areas of the heat shield without problems. This provides for more effective and improved cooling.
In a particularly favourable development of the present invention, the heat shield is provided with stud bolts which can be led through openings in the metering panel. Separate bolts or similar means are, therefore, dispensable. Attaching the stud bolts to the heat shield also ensures high operational safety by avoiding the risk of parts coming off and entering the combustion chamber interior during operation.
In accordance with the present invention, the sleeve is preferably attached by means of retainers on the metering panel. In a favourable development of the present invention, these retainers are attached to the stud bolts of the heat shield. Additional bolts or threaded fastenings can, therefore, be entirely dispensed with. The entire construction is simplified considerably.
In a particularly favourable arrangement, each retainer holds two adjacent sleeves.
This allows for smaller retainers, with each retainer required to cover only a partial area of the sleeve. This arrangement is also beneficial in terms of the supply of cooling air.
For maximum simplicity of attachment of the cowling, at least one stud bolt is provided on the retainers. Thus, the cowling can simply be put onto the studs and bolted from the exterior.
For attachment and positioning of the cowling it is particularly favourable to locate the rim of the cowling in a groove in the metering panel. This design safely retains and centers the cowling. Furthermore, the groove will restrain the cowling in the case of a bird strike. The restraint provided by this design will, in this case, prevent the simply designed sheet-metal part from plainly bending out by enabling it to transform much more energy into deformation work, thereby reducing the degree of deformation and ensuring the continued operation of the combustion chamber head for the remaining operating time.
According to the present invention, the metering panel is provided with a plurality of cooling air holes, as known in the state of the art.
To improve the cooling of the heat shield, it can be favourable to provide it with a rim which abuts a collar of the sleeve, this rim extending in the upstream direction and being led through an opening in the metering panel. The height of the rim is selected such that, in the installed condition, the rim extends appropriately beyond the upstream side of the metering panel, thereby allowing the cooling air to freely access the central zone of the heat shield even if the collar of the sleeve abuts the cylindrical rim.
The design according to the present invention enables a defined gap to be provided between the outer wall of the cylindrical rim of the sleeve and the inner wall of the rim of the heat shield, this gap permitting a radial and circumferential relative movement of a fuel nozzle and the combustion chamber head. The size of the collar of the sleeve exceeds the outer diameter of the rim of the heat shield by the max. possible amount of movement, this feature enabling the space before the metering panel to be sealed to the combustion chamber against undesired leakage air even if the max. possible movement of the sleeve should take place. This provides for advantageous assembly and operating conditions.
Furthermore, the gaps between the sleeve and the retainers are particularly advantageous since they provide for sufficient clearance necessary for thermal compensation. On the other hand, provision is made for the secure positioning of the sleeve. The sleeve is securely and adequately positioned by the left or right part, respectively, of the adjacent retainers. Accordingly, each retainer secures two adjacent sleeves. As already mentioned, the retainer itself is fitted to the stud bolts of the heat shield and secured to the metering panel with appropriate nuts. In accordance with this invention, the retainer can accordingly also be designed as a support for the cowling, as already mentioned in the above.
The design proposed in the present invention enables the individual components to be separately manufactured and safely assembled. This provides for a high degree of flexibility also in terms of the candidate manufacturing processes and materials.